I am new to Configuration Management, though I have been familiar from a broad perspective with ITIL/ITIM/ITSM for the last year.
I have been tasked with implementing the database and process. I am currently looking for feedback and guidance based on real-world experiences. If anyone has anything to offer I would be greatly appreciative. I am even willing to buy you dinner if you are in or ever visit the Tampa, FL area. Thanks you!

Begin by identifying critical systems (your continuity plans, annual report, business departments should be able to tell you what they are). You will then need to pull together two views or perspectives on the infrastructure. The first will be the "accountability" view. This will be a logical picture of who owns or is responsible for the various pieces of the infrastructure. Who owns the servers? Who owns the mainframe? By "owning" I mean whose head will roll if something goes wrong with that component. Identify who provides services to whom. Once you know the owners, start creating a logical diagram that shows who is accountable to whom. This will result in something that looks like a value chain. This will become the basis for your service chains.

Now you can create the second view. You may already have this in terms of topologies, physical infrastructure diagrams, etc. The second view shows the physical and functional relationships between pieces of the infrastructure. This will become the basis for your CMDB and and CI structure.

Now comes the hard part. You must overlay or map the first view on top of the second view. This will show you gaps in your ability to deliver services and to monitor your infrastructure. Anything that does not directly support your service chain should not initially be in your CMDB. In other words, your services provide the requirements for what goes into your CMDB and how your Config process works. Once you have an initial CMDB, just keep repeating the process, building on what you already have.